Release and surface-passivation techniques of stiction-free micromachined structures

摘要

Mechanical instability and stiction of surface structures are troublesome problems in the microfabrication of microelectromechanical systems (MEMS). They are particularly critical when separation gaps are in the sub-micrometer scale. Fabrication-related stiction is usually the result of the rinse-and-dry procedure following the sacrificial layer etch in the structure-release process. The operation-related stiction is the result of over-range operation or capillary condensation after packaging resulting from operation in humid environment. We will present a survey and analysis of various release methods used to hedge stiction problems during fabrication, and then draw a useful comparison among various techniques. Likewise, we will examine some ideas put forward to remedy against post fabrication stiction. The underlying physics for stiction is fundamental to our understanding of the various forces coming into play on the structures in the dimensional scale most utilized in MEMS. We will have a brief look at the proposed theory for modeling these phenomena.